1. Field of the Invention
The present invention relates to automobile assembly line apparatus; and more particularly, to apparatus for positioning main body parts of an automobile for assembly in an automobile assembly line.
2. Discussion of Prior Art
Presently, on most automobile assembly lines, various types of automobiles, such as two-door and four-door cars, coupes, and vans are produced in an irregular order, so that assembly equipment having ready adaptability to a change in auto body types is increasingly demanded.
To meet such demand, a type of apparatus, referred to as a circulating jig, is conventionally used. This type of apparatus is provided with a plurality of jig trucks, on each of which is mounted a body part manufactured exclusively for a particular type of automobile. These jig trucks are then conveyed over an endless path, or in other words circulated, so that the required body parts are conveyed to the assembly equipment as desired. More specifically, and with reference to FIG. 6, this type of apparatus includes a jig truck 51 with an under body A mounted thereon, and a jig truck 52 with a side body B mounted thereon. The jig truck 51 for the under body A is first placed on a surface plate 53 at the assembly equipment location; then the jig truck 52 for the side body B is conveyed to the assembly equipment location. After both jig trucks 51 and 52 are coupled and positioned by a coupling member 54, the under body A and the side body B are welded by welding equipment (not shown).
In the above described conventional circulating jig type of apparatus, each of the jig trucks is configured exclusively for a particular type of automobile; thus rendering it necessary to configure many different types of jig trucks in accordance with the types of automobiles to be manufactured. In addition, the apparatus for supporting the jigs is complicated. Therefore, the previously described jig trucks, such as 51 and 52, are used only for assembly of the under body A and the side body B. As a result, assembly of the roof, cowl, upper back, lower back, etc. is carried out in another assembly process.
In view of the above, a Japanese Patent Application No. 131271/1984 filed by the inventors herein and assigned to a common assignee, proposes to provide a vehicle body assembly apparatus as shown in FIG. 7, in which a distinct type of jig 57 includes a jig frame 55, having a uniform configuration; and having jig members 56 removably mounted thereon. Jig members 56 are constructed exclusively for a particular type of automobile, and are replaced as required for assembly of different types of automobiles. As shown in FIG. 7, for example, the different body parts are placed on the distinct jig 57 and brought to the assembly equipment at the same time. This apparatus is advantageous in that it enables a single jig, such as 57, to hold a plurality of body parts, such as a roof C, a cowl D, and an upper back E, as illustrated; and thus permit the assembly of such body parts in P the same process with the assembly of the under body and side body parts, to complete the assembly of the main body.
In a vehicle body assembly apparatus having the above described distinct type jig 57, the positioning of such jig at the assembly equipment, with a body part, such as a roof, cowl, or upper back mounted thereon, is accomplished by a positioning device located on the conveyor side of jig 57. Therefore, positioning of the jig is conducted from a distance, which makes it difficult to ensure the absolute positions of the body parts. Additionally, such a positioning device is unavoidably made large in size and complicated in construction.